Self-folding strut for airplane landing chassis



April 18, 1939. R. L. LEVY 2,154,984

SELF-FOLDING STRUT FOR AIRPLANE LANDING CHASSIS Filed April 2, 1937 2 Sheets-Sheet 1 R. L. LEVY A ril 18, 1939.

SELFFOLDING STRUT FOR AIRPLANE LANDING CHASSIS Filed April 2, 1957 2 Sheets-Sheet 2 Patented Apr. 18, 1939 UNITED STATES PATENT FFHCE SELF-FOLDING STRUT FOR AIRPLANE LANDING CHASSIS Application Apr-H2, 1937, Serial No. 134,641 In France May 26, 1936 4 Claims.

This invention relates to retractable landing chassis for airplanes, and it concerns a so-called self-folding strut, in this sense that it has the property of folding or of coming in extended position by a stress which is developed within the device itself, that is to say without this stress taking a bearing on the airplane.

The retractable system, in which this self -folding strut intervenes, is connected to the airplane by only two fixed points about which it can rock, the distortion of the self-folding strut, by a stress within the latter, having for eflect to determine this rocking movement 'or oscillation in one direction or the other.

The self-folding strut is essentially constituted by two elements pivotally connected by a third and so-called coupling element, the relative movements of the two extreme elements, relatively to the coupling element, being governed by a suitable kinematic law, this unit being, moreover, combined with any driving member (pneumatic, electric, hydraulic member, sandow, etc.) carried by the self-folding strut and taking a bearing on one of the elements for engaging 35 with one of the two other elements, in order to determine either the folding or the extension'oi' the strut.

The two extreme elements are pivoted, one to a a fixed point of the airplane, the other to a point 30 of the landing chassis which is to be retracted.

In the embodiments described hereinafter, the kinematic law governing the displacements of the extreme elements is realized'by means of links, or gears, but the invention extends, of course, to

35 the use or any other equivalent means.

In the accompanying drawings:

F18. 1 is a side elevation showing a first embodiment of the invention.

Fig. 2 illustrates, on an enlarged scale, the

40 members for connecting together the two elements of the self-folding strut, at the folding point.

Fig. 3 is a side elevation showing a modification.

45 Figs. 4 and 5 are partial views corresponding to the preceding one, the first showing the strut in extended position, and the second showing said strut in folded position.

Referring to the example illustrated in Figs. 1

50 and 2, it will be seen that the self-folding strut is constituted by two elements A-B connected by a coupling element constituted herein by a link, or a pair of links, l-l, on which the elements A-B are pivoted at 2-4.

55 At its end opposed to the coupling element, the

element A is pivoted at 4 on the carrying strut J of the wheel R. This strut J, which is provided for instance with a shock absorber, can pivot about a fixed pin 5 on the airplane.

This element B of the self-folding strut can 5 pivot about a pin vli, .also fixed on the airplane V.

The pins 5-6 constitute the only two solid points through which the wheel and its retracting system are connected to the airplane.

The kinematic law which co-ordinates the i0 movements of the elements A-B is enforced by a link I which is pivoted, on the one hand, at 8, on a boss ll) of the element A, and on the other hand, at 8, on an extension ii of the element B.

The driving element, arranged within the re- 16 tracting device, is constituted, in this embodiment, by a jack l2 which bears, on one side, on a joint i3 of the element A, and. on the other side, engages, through a joint ll, with a double triangle l5-|5, rigid with the coupling mem- 20 her l-l.

In the extended position illustrated in full lines in Fig, 1, the system cannot accidentally open, as the jack l2 prevents any displacement corresponding to the folding of the strut A--B in one direction or the other.

By causing retraction of the jack l2 (operating, for instance, hydraulically) the strut is caused to fold, according to the arrow by angular displacement of the elements A-B about the pivotpins 2-3, which themselves are movable in space.

Simultaneously, the element B pivots about the fixed point 6 and the carrying strut J pivots about the fixed point 5, according to the arrows P, so that, when the movement of retraction is terminated, the articulated device has come to the position illustrated in dot and dash lines in Fig. 1.

For this position, the index I is added to the reference numbers and letters designating the various parts or members.

It is to be noted that, in the extended position of the strut, the links il bear against an abutment member l6 provided on the element A. Likewise, in the retracted position, the arm B rests on a bearing member I1 rlgid with the triangle I5 -l5 I In the example of Figs. 3 to 5, the interdependency of the movements of the two elements A--B of the self-folding strut is ensured, no longer by the link 1, but by toothed wheels ll-IQ, meshing together and rotating on the pins 2-3, the links l-l connecting, as previously, the tw extreme elements of the strut. 5

What I claim as my invention and desire to secure by Letters Patent is:

LAretractablelandingchassisiorairplanes comprising a carrying strut, a pivotal connection betweensaidstrutandailxedpoint orthe airplane, a self-folding strut including two outer elements and a third coupling element, a separate pivotal connection between each or the two outer elements and said coupling element, means pivotally connect-ins one end 0! the self-folding strut to said carryihl strut. means pivotally connecting the opposite end 01' said strut to a fixed point of the airplane, an expansible driving member separate from each of the three elements of 5 the strut and pivotaily connected at one end to one of said elements and at the other end to another oi said elements, and means separate from said expansible driving member whereby each positlon or one of the outer elements is caused to 0 correspond to a definite position of the other outer element.

2. A retractable landing chassis for airplanes comprising a carrying strut, a pivotal connection between said strut and a fixed point of the airzs plane, a seli-iolding strut including two outerelements and a third coupling element, a sepa-- rate pivotal connection between each of the two outer elements and said coupling element, means pivotally connecting one end of the self-folding 80 strut to said carrying strut, means pivotally connecting the opposite end of said strut to a fixed point of the airplane, an expansible driving member separate from each oi. the three elements of the self-folding strut and pivotally connected at its opposite ends to said coupling element and another of the elements of said sell-folding strut, and means separate from the driving member whereby each position or one of the outer memhers is caused to correspond to a definite position of the other outer member.

3. A retractable landing chassis for airplanes comprising a carrying strut, a pivotal connection between said strut and a fixed point 01 the airplane, a self-folding strut including two outer elements and. a third coupling element, a separate pivotal connection between each oi the two 6 outer elements and said coupling element, means pivotally connecting one end of the self-folding strut to said carrying strut, means pivotaily connecting the opposite end of said strut to a fixed point of the airplane, an expansible driving memi0 ber separate from each of the three elements of the strut and pivotally connected at one end to, one of said elements and at the other end to another of said elements, and a link separate fromsaid driving member connecting the ad- 15 jacent ends of the outer elements of the sellfolding strut whereby each position of one of the outer elements corresponds to a definite position of. the other outer element.

4; A retractable landing chassis for airplanes 20 comprising a carrying strut, a pivotal connection between said strut and a fixed point of the airplane, a self-folding strut including two outer. elements and a third coupling element, a separate pivotal connection between each of the two outer elements and said coupling element. means pivotally connecting one end of the self-folding strut to said carrying strut, means pivotally conmeeting the opposite end of said strut to a fixed point of the airplane, an expansible driving member separate from each of the three elements of the strut and pivotally connected at one end to one of said elements and at the other end to another of said elements, and intermeshing gear segments separate from said driving member and carried respectively by the adjacent ends or the outer elements of the self-folding strut whereby each position, of. one of the outer elements is caused to correspond to a definite position of the other outer element. 0

RENE LUCIEN LEVY. 

